CustomInventory items are special items that allow some very primitive scripted functionality using its states. The base class CustomInventory is never used directly. It is always the base class for items defined in DECORATE.

Using in DECORATE

Tip: Players, Monsters and pretty much everything else can obtain a CustomInventory and be affected by its Pickup state, with the exception of other inventory items.

The behavior is as follows:

All code pointers in the Pickup state sequence are called when the item is being picked up. The sequence is successful when the last called function in the state doesn't return failure explicitly; you can also use ACS_ExecuteWithResult to set the result from ACS. Success can be overridden by terminating the state sequence with fail instead of stop.

Tip: Jumping functions always set success to false.

If the Pickup sequence returns successfully the behavior depends on the presence of the Use state:

If there is no Use state the item will be removed from the map and not be placed in the actor's inventory.

If there is a Use state the item will be placed in the actor's inventory.

If the item has a Use state and is being used by the player the Use state sequence is called. Failure or success are determined the same way as for the Pickup state. If the sequence returns successfully the item is removed from the inventory. Note that due to this special behavior, the Use and Pickup states will ignore all frame durations and shouldn't be looped, attempts to do to so may result in the sequence being interrupted by the engine; every frame will execute within the same tic.

If the item is being dropped by a monster the Drop state sequence will be executed and the item will never be spawned. This is mostly there for special actions that can be taken by Strife conversation scripts. For regular monster death actions there are better and more flexible way to achieve the same.

Notes:

State jumps should use an actual string instead of an offset number to perform the jump to guarantee it does what it's supposed to do for the Use state.

To make an item that's able to be picked up with conditions (excluding the Inventory.MaxAmount property), the inventory item will have to perform a function such as A_RailWait last in the state, especially after jump functions. The +INVENTORY.ALWAYSPICKUP flag should not be used in this case, because even if the sequence fails, the item will still disappear. Instead, after all conditions are met, you should perform a function akin to the described above to signify success.

CustomInventory items can modify the picking actor's user variables but the following conditions apply:

The same user variable needs to be defined in both the actor and the CustomInventory item, if they are going to use said variables in expressions. Otherwise, A_SetUserVar and A_SetUserArray can be used for setting numbers directly without the need to define them.

The CustomInventory item can modify variables of the owner only through its Use state.

A jump to the Use state will NOT be treated the same as the actor actually activating it. For this, the +INVENTORY.AUTOACTIVATE flag must be present if it's for anything non-player related.

CustomInventory items cannot be used to "fetch" variables directly. They can perform jumps based upon the current actor's variables that are defined, and execute DECORATE action functions and ACS scripts accordingly, and they can modify that actor's variables in particular, but nothing else. Once used, the CustomInventory item loses access to its variables, gaining direct access to the owner's variables instead.